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Paper | Regular issue | Vol 85, No. 9, 2012, pp.2241-2250
Published online, 11th July, 2012
DOI: 10.3987/COM-12-12526
Synthesis of Procyanidins C2 and C1 Using Lewis Acid Mediated Equimolar Condensation

Yukiko Oizumi, Miyuki Katoh, Yasunao Hattori, Kazuya Toda, Koichiro Kawaguchi, Hiroshi Fujii, and Hidefumi Makabe*

*Sciences of Functional Foods, Graduate School of Agriculture, Shinshu University, 8304 Minamiminowa-mura, Kamiina-gun, Nagano 399-4598, Japan

Abstract

Synthesis of procyanidins C2 and C1 was achieved via a stereoselective intermolecular condensation of equimolar amount of dimeric catechin or epicatechin nucleophile and monomeric catechin or epicatechin electrophile using Lewis acid. In the case of synthesis of procyanidin C2, AgBF4 and AgOTf afforded condensed product in excellent yield. As to the synthesis of procyanidin C1, Yb(OTf)3 was effective for equimolar condensation.